Edge chatter

[frogwood]

Starting to cut some wood with a bt48 I purchased used. I am cutting a baluster for porches that has many curves. I am cutting 3/4 cypress which is fairly soft. I am cutting 1/4 deep each pass @ 1.8 inches per second - climb cut. I also did a clean up cut at full depth cutting off .0175 @ 1.5" per second also climb cut. I am getting an edge that is not as clean as I would like it. It might be acceptable for what I am making but I feel like it should be better. I am using a 3/8 bit. The 1st one I used was one recommended to me by the manufacturer. It was a upcut spiral and supposed to give a clean cut in softer woods a # 52-701. It left a pretty rough edge. I then tried an amana 43414 two flute straight - no spiral. It did have a 10 degree hook that was supposed to make it a little more agressive. The second bit did better but still is not as smooth as I think it should be. In the center of the piece is a 2.125 circle and it seems like in that perfectly round cut the edges seem to be smoother.

I have tried to wiggle and giggle the carriage and router but nothing seems to be loose. I have the router not the spindle. I designed the piece probing
a part I had and then went in and did node editing to clean it up and make everything smooth. I've been wondering if the machine is hitting these nodes or if everything gets smoothed out when converted. The edges look like chatter though and not like it is hitting specific points in a file. I am using vacuum hold down but that seems solid. I can not move the blank as hard as I try manually. I am not cutting all the way through the part and loosing vacuum.

Any advice on bit choice, depth, speed or something to adjust?

Thanks

[dlcw]

Do you have some pictures to show what the chattering looks like?

[jerry_stanek]

have you tried a conventional cut.

[fozzyber]

Climb then conventional,, I thought I had problems until I tried this

[garyb]

First of all Allen you have the wrong tool.
The 52-701 is a high helix tool designed for soft plastic such as ABS, HDPE and the likes.
You should be looking a the 52-200 series for wood
Gary

[Gary Campbell]

Can you post the file? If the circle cuts well, it may be in the file. Probe interpretations dont always come out perfect.

[frogwood]

I'll reply to several of your comments in this email. Thanks for your help.

The 52-701 was recommended to me by the maker. They said it was for plastics but worked good in soft wood but it caused a lot worse edge than the straight 2 flute plunge that I tried after it. The second bit I tried has a 10 degree angle so perhaps trying one without the 10 dgree. However it cut the circle and straight parts of the piece smoothly.

The circle in the center of the cut was creater witht the circle tool in partworks. Also after taking another look at the piece the straight cuts that line up with the X ad Y axis were smooth - not chatter. It's just where the curves are located where the chatter is.

I did try conventional direction but I have not tried it with the less agressive bit. I used to cut these parts with a pin router and I would get chunk now and then get knocked out of the edge where the bit was hitting the grain a certain way. So would you say cutting climb for the main cutting and then conventional for the clean up cut? How much would you say to take off on the clean up cut? I was using .0175,

Probing. After probing I went back in and took a considerable amount of time going all around the piece and on the inside moving nodes to smooth out the vectors. However the circle was created with the partwork circle drawing tool and the square sides and top and bottom of the piece just have nodes at the corners and not all along the straight cut. The circle and these straight cuts are smooth.

I went back and did some more wiggling on the machine. I was able just to get a very slight move in the axis. It was ever so slight. It seemed to be a movement of the shaft of the motor if that is possible? Should there be any movement if you take the motor and just try and move the shaft? The machine I bought was supposed to have had light use. Was not in a shop situation. The movement was so slight that it was difficult to see. The pinion that was easy to see on the X axis was tight on the shaft.

I'll see if I can take some pics and post the file.

Allen